1. Field Of The Invention
This invention relates to internal combustion engines of the special type known as the Bourke engine, certain features of which were the subjects of U.S. Pat. Nos. 2,122,676, 2,122,677 and 2,172,670 and the history and details of which engine are more fully described in a publication entitled Bourke Engine Documentary by Lois Bourke, copyrighted by the author in 1968, and printed by D. D. Enterprises of North Hollywood, Calif. 91601.
2. Description Of The Prior Art
The principal prior art relating to the present invention comprises the three United States patents and publication heretofore identified, together with a patent application Ser. No. 726,321, filed May 18, 1934, by Russell L. Bourke, which is referred to in U.S. Pat. No. 2,122,676, but on which application no patent ever appeared to have issued; and various engines made and operated as described in said publication.
It is well known by persons familiar with the Bourke engine that it is comprised of pairs of cylinders with each pair coaxially aligned and disposed back to back with the piston rods extending from the pistons reciprocating in each of these cylinders also coaxially aligned and being joined by a yoke. The center of the yoke is transversely slotted to receive the throw of a crank so that, as each pair of pistons and their yoke-joined piston rods reciprocate as a unit, the crank throw will not only be reciprocated with and in the direction of the yoke, but it will also reciprocate transversely in the yoke slot. Thereby there is imparted to the crank shaft the desired rotary driving motion from the reciprocation of the paired pistons which are interconnected through their rods and the yoke to move reciprocally as a unit.
While the theory and principle of operation of the Bourke engine are such that this engine offers many advantages over more conventional internal combustion engines, certain mechanical problems have been observed in Bourke type engines which have heretofore been built and tested, and these problems appear to have contributed to the apathy of engine builders toward the Bourke engine. Among these problems have been:
1. The piston rods have been secured internally from the piston head in such a manner that the full thrust load of the piston has been carried by each of (a) a pin passed diametrically through the piston walls; (b) a yoke on such pin; and (c) a wrist pin passed transversely through the end of the piston rod and said piston yoke. Over long sustained operation of the engine, it is felt that such load carrying pins and yoke may be subject to such possible metal fatigue as to cause a fracture of any one of them with resulting serious damage to the engine. In addition, the pin extending through the piston walls has not been anchored against axial displacement so that such displacement can occur, and when it does, one end of the pin may gouge the wall of the cylinder in which the piston is reciprocating.
2. It has also been found that in Bourke engines heretofore built and tested there has been created an undesired side loading effect as the piston reciprocates in its cylinder. This is because, at least in part, of the articulated manner in which the piston thrust load has been conducted to the piston rod through the pins and yoke described in the preceding paragraph.
3. In the yoke and crank throw assemblies of Bourke engines heretofore constructed and operated, the theory of construction and assembly has been to provide a roller load bearing which rolls first in one direction; then, after rolling a certain distance, reverses its direction of roll and then rolls for such predetermined distance in the opposite direction transversely of the axis of movement of the piston, piston rod and yoke assembly. It has been found in practice, however, that, as the engine speed increases, insufficient time is provided to enable the roller bearing to reverse its direction of roll within the yoke slotting. As a result, the driving load is imposed on limited arcuate surfaces to cause wear to the same and to develop high frictional losses.
The foregoing problems appear to be among those which appear as yet to have prevented widespread acceptance of the Bourke engine construction among engine builders and automotive companies, despite the many advantages which the Bourke engine construction and its operation offers over present popular engine designs.